I’d like to hear how others deal with heatwaves such as I experienced here this year with temps in the 90’s up to 105 F. I added kelp extract and aloe vera juice to the water and when it got over 90 I put under an umbrella and when over 95 (with great difficulty and damage) moved all plants inside for each of two hottest spells) Other than the damage from moving them (broken off branches and abraded ones which went bad). What are other outdoor guys in pots doing about heat? Mine are larfy and trichomes sparse so these are headed for the ice hash pile.
Gdub welcome. I ran into an even higher heat wave as I live in Las Vegas NV and we went to 115 + for almost 3 weeks and 110-115 + for over a 6 / almost 7 week period.
I had too many plants, too large in containers (10-13gal -way to heavy to lift) and nowhere near enough room to move indoors. I erected a shade net and watered frequently - sometimes 3 / 4 times a day. I even hosed my containers to cool off the root zone. Watering were cooled water and shallow, not heavy. I managed to keep less than 40% of my crop and growth was affected on all plants. The strains I expected to survive did not. WonderWoman came back and i harvested maybe 3 oz ttl smoke-able. The rest were like 1/2 to 1 oz crops. SO disappointing. I will change my season and try planting earlier, switching to 12/12 sooner so I can flower before the heat sets in. I will have to create blackout covers for my plants. I usually go with a dozen in the flower pots and 5 in the garden. I am painting all my pots white to reflect the heat. I am lining interiors with foam insulation to protect root zone and adding more perlite so I will not have as much moisture retention which will heat up and cook the plants. I use kelp and other root protection but they were no avail in my hot summer. I will see what happens this next year as I try to implement my solutions. I used the shade screens that the nurseries use. I was able to drop 10 degrees but Vegas winds blow at that high temp and that was impossible to overcome.
If you have any insights, I would appreciate them. For now, I am tent growing auto only for winter and move them in and out as we still are enjoying 70+ degree temps here during the day.
I’d think Las Vegas area would have it’s own growing schedule to avoid these temps. A few things; an outdoor umbrella blocks more than the shades you’ve described and is cheap. Mine is on rollers in an extra heavy base to prevent tipping in the high winds here. I use kelp extract as well and add aloe vera juice for better water uptake when plants drink the most. I may also do the pot treatments you describe, as I’m spraying the existing ones down to cool them like you. I’ve moved the entire grow into my garage twice this year, damaging the 8’ tall ones as they brushed against walls and cielings on the way. But this I think saved this years grow for the most part even after tossing the damaged parts I have plenty for all uses again. Quality suffered as well somewhat. All are curing in my wine cellar (at 64’F and 55% RH) after hanging in their for 10 days (very slow dry/cure makes for very good stuff!) they are now all in glass jars waiting another two months to finish curing.
Patience…After 50 years at this, I still do not have any. My cures have been in jars for about 2 weeks now and there is no way to resist smoookin them. Just your average pothead. I have used the aloevera as it grows freely here. Umbrella - would need like 6 to cover my area. People would start to think I had a restaurant / cafe in my back yard. Can’t have that as is illegal if within 25 miles of any dispensary and boy, they are everywhere. The shade screens blocked the sun pretty good, it was the HOT winds that killed me. Here in vegas, hottest part of the day is 5pm. Angle of the sun is pretty low and I am able to block an entire west view but that wind just cooks everyhting. Our humidity is like 6%. Light meter still gave me 900-1100 range with screen cover. Except for heat, that is enough for them to grow. Issue becomes amount of sunlight when we start early. I start all indoors and transplant using 3" peat cup for seeds started in peat pods 39m. I drop autos in 3 gal cloth bags, photo into my 40/50l pots and half doz right in the garden. I grow beans (for nitrogen), tomato (allows me to see calcium - no tomato end rot, no calcium issue). I make my own soil for outdoors and blend for my tent. I am planning to start phenos in Jan so I can get in ground by feb. We are usually 80+ by then. The hard part is going to be the flowering times. Hard to KEEP 12/12 when you get 15.5 hrs of sun. I am starting to keep large cardboard boxes that I can cover and use as blackout covers. Just a little light peek is a killer in flower mode
The addition of silica will help to protect the plant from heat stress.
Just to add to what @Darkheart420 said. Food grade diatomaceous earth is a good organic source of silica and can be used as a soil amendment. Just mix it with your soil before the grow.
If your soil is already mixed just top dress with the DE just like you would for pest control.
Welcome @Gdub. This is what I did for my outdoor plants to get them through heat waves in CA.
When I mix my soil I always amend with DE and some silica. I also use about 50% coco coir in my substrate. It helps retain moisture to keep plants watered and it runs cooler.
Double potting. I get 10 gallon ceramic planters to use as a base and I set my 5 to 10 gallon fabric pots in them. Keeps the sun off the fabric pots and keeps the roots cool.
Evaporative cooling. Water in early morning so as the water evaporates through the day it keeps plants a few degrees cooler. If double potting plug the drainage holes in the bottom pot and fill the first few inches with sand and gravel or perlite. Fill the bottom of the pot with water. The gravel keeps the pot from sitting in the water and it cools the plant as it evaporates.
Kelp and seaweed extract. You can use the powder as a soil amendment or with waterings. The liquid kelp or seaweed extract use in waterings. It has lots of micronutrients as well as auxins and other plant hormones that help regulate temp and size.
Always choose a location with lots of airflow. Never underestimate the cooling power of even just a light breeze.
Choose an area near trees or other cover crops for partial shade and plant on the eastern side so when then sun is highest your plants will be in shade.
Early morning foliar feedings with calmag. Magnesium strengthens stems and leaves through foliar feeding and makes them more resistant to heat and pests.
Kushman chiropractic. Not only does it increase yield but those increased pathways also allow for more water in the plants which also leads to plants that run cooler and resist heat stress.
Great information. Thank you for such an informative process to deal with heat. This one goes in the books